The forgotten man of telescope making

Sometime in the late 1970's John Dobson invented a type of telescope. This
was driven by necessity, in that cheap materials were relied on the build a
telescope that resembled a cannon and used large bearings of Teflon and
Formica.



I owned such a telescope, a 13.1 inch dobsonian sold by Coulter Optical back
in the 1980's. It was a beast, and was almost impossible to move. Coulter
also sold 17.5 inch and 29 inch Dobsonian models in blue livery. Their bulk
is the reason that I don't see any Dobsonian telescopes around today. There
was a brief period when there were many such telescopes being made, as
recorded in the pages of the now defunct TM magazine. They were made of
plywood or chipboard, with a tube of cardboard. This design allowed a
considerable number of amateurs to afford a larger aperture telescope.



What changed this was the publication in TM issue 17 in 1981 of Ivar Hamberg
's truss tube alt-az telescope. Despite them being called Dobsonians, they
bear as much relationship to Dobson's design as the VCR does to DVD. Almost
all modern alt-az mounted telescopes these days copy this design, which has
been considerably refined by David Kreige. These Kreigescopes are called
"Obsessions".



Ivar's article in TM#17 introduced the collapsible truss tube, allowing
disassembly and transport to dark skied from urban areas. This opened up a
whole new field of large aperture deep sky observers, a whole new trend.



Ivar's design has been further evolved to some ultra light designs to
reinforce this trend.



Yet Ivar is almost forgotten. They are not called "Hambergians". His
contribution is almost forgotten. Why? Is it that Dobson is a citizen of the
USA whilst Ivar is from Stockholm, Sweden? Is there a jingoistic bias here?
Does everyone really think that Ivar's design is really just another
Dobsonian, just because it uses an Alt-Az mounting, just like Herschel used?
I don't think so. I think Ivar needs a bit more recognition than what he is
currently given.

StarDust wrote:

Sometime in the late 1970's John Dobson invented a type of telescope. This
was driven by necessity, in that cheap materials were relied on the build a
telescope that resembled a cannon and used large bearings of Teflon and
Formica.

That seems a bit simplified. Try

http://www.johndobson.org/

More to it than just inventing or developing a telescope mount, it seems.
Much more.

--
Anders Thulin ath*algonet.se http://www.algonet.se/~ath

StarDust wrote:


Yet Ivar is almost forgotten. They are not called "Hambergians". His
contribution is almost forgotten. Why? Is it that Dobson is a citizen
of the
USA whilst Ivar is from Stockholm, Sweden? Is there a jingoistic bias
here?


Hi:

What's your evidence for that? It ain't "jingoism," it's _ignorance_. I
have never heard of him--and I suspect the same goes for most other
American amateurs. The reasons Mssr Hambergian is not "remembered"?

--Though the truss tube idea is incredibly poplular and important for
larger scopes, the basic _and MOST important_ idea, which this design
still uses, an alt-az mount using large formica-teflon bearings, had
become identified with John Dobson for some time before the truss tube
idea came to the fore. Yes, these modifications were important, but
most people look upon them as "just" mods of the basic idea J.D.
popularized.

--Again, most people have never heard of this person.

--It is my impression that the truss tube idea was something being
worked on by several people more-or-less simultaneously, and that
giving one person credit for the design would be a little erroneous.
The truss tube scope amateurs use today is a mixture of innovations
devloped by people like Dave Kriege, Tom Clark, Randy Cunningham, and
many more that I, not being a Dobber, have probably forgotten. ;-)

I believe in credit where credit is due. If you think this person
deserves recognition as the "inventor" of truss tube scopes, spread the
word. Give presentations on him at star parties and clubs. Write
articles for astronomy mags, etc.

Peace,
Rod Mollise
Author of:_Choosing and Using a Schmidt Cassegrain Telescope_
http://members.aol.com/RMOLLISE/index.html

Stardust - I'd have to say the accuracy of most of your post is largely
in question.

First off, John Dobson (perhaps to the surprise of many) was hardly the
inventor of a new or revolutionary telescope design. He simply
re-popularized a telescope design that (save for the thin primary
mirror) had been in use for more than 150 years previously but employed
less expensive materials. Commercial telescope makers in England and on
the continent were using the design widely well before the turn of the
20th century, as a check of early advertisements will indicate. Indeed,
fixed military shore batteries were mounted in essentially this same
manner for centuries.

Solid-tube Dobsonsian telescopes, faithful to the original 1970's
Dobson scopes, continue to be by far the most popular of all medium to
relatively large (8" - 16") Newtonian telescope types - not truss tube
designs, which are much more typical of high-priced commercial units
than of lower-priced or homebuilt scopes. And at least in the United
States, collapsible truss-tube scopes are down right rare. So is it
really surprising that Ivar Hamberg's name is not linked to any
particular scope design and has gained little recognition? Probably
not.

CNJ999

Rod brings up excellent points. (His use of the word "popularize" is key.) I
think the reason John is a household name is that he goes everywhere and
talks to anyone and everyone. The man is a tireless speaker, traveling the
world. (Just NEVER ask him about his train trip across Russia and his
experience with cabbage, you have been warned!) He is incredibly charismatic
and enigmatic. John stirs up excitement (and a bit of controversy)
where-ever he goes. John is almost as good at marketing himself as Madonna.
I may not agree with his cosmological views but he is darned fun to be
around.

Like others, I have never heard of Ivan but you have sparked my interest
and I will look him up and see what I can find. (Maybe Ivan is another
Nicola Tesla of history?)

Dawn Baird-Chleborad
www.wodenoptics.com
www.astronerds.com

On Sun, 20 Feb 2005 20:11:01 +1100, "StarDust"
wrote:

Sometime in the late 1970's John Dobson invented a type of telescope. This
was driven by necessity, in that cheap materials were relied on the build a
telescope that resembled a cannon and used large bearings of Teflon and
Formica.

Dobson didn't invent a type of telescope. He really didn't invent
anything. On the technical front, what he did was take advantage of some
new materials to modify a type of mount that had been around already a
long time.

But what he really did was to become a spokesman for budget astronomy.
He popularized inexpensive, large aperture telescopes. He still does. It
is his strong public presence that is responsible for his fame.


Ivar's article in TM#17 introduced the collapsible truss tube, allowing
disassembly and transport to dark skied from urban areas. This opened up a
whole new field of large aperture deep sky observers, a whole new trend.

Maybe, but it was just another technical adjustment. We remember
Serrurier for the truss design itself- making it collapsible is
interesting, but no more exciting technically than using formica and
teflon instead of more expensive bearings. I guess that if Hamberg had
spent a generation pounding the streets of Stockholm like Dobson has
done in San Francisco, his name would be more widely known.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

One thing, the home telescope builder still, for the most part, follows the
Dobsonian way, my Babylon 8 which came to be with the help of many others is
a soild tube Dobsonian that has a bit of a mod so it's eayer to use for
Sidewalk Astronomy.
I know I've read of and seen home made truss scopes too, and as others have
said, I've never heard of the one you posted about. There's one small
company right here in Calif. I wish I could win the Lotto, as then I could
afford to have them make me a verson of their design to fit my B8's mirror,
it's a cross between closed tubes and truss, as it's a framework that has
two sections, one that slides into the other for transportaion. Hay they are
in the FAQ too. But until that day comes, I use my B8, it might not be as
good as it could be, but I was the only one to do the hands on work of
building it and it's the best I could do.

As far as the store bought scopes go, the soild tube Dobsonian still in the
number one type of scopes sold and can be found very easy.

--


SIAR
www.starlords.org
Telescope Buyers FAQ
http://home.inreach.com/starlord


"StarDust" wrote in message
...
Sometime in the late 1970's John Dobson invented a type of telescope. This
was driven by necessity, in that cheap materials were relied on the build
a
telescope that resembled a cannon and used large bearings of Teflon and
Formica.

Chris L Peterson wrote:

Maybe, but it was just another technical adjustment. We remember
Serrurier for the truss design itself

A funny thing, but 90% "remember" Serrurier trusses wrongly. The
Serrurier truss extends from the pivot to the secondary, and another
truss extends from the pivot to the primary, balancing deflections and
keeping the planes of the primary and secondary aligned.

Just sticking poles on the primary box, doesn't make it Serrurier trussed

Steve

On Sun, 20 Feb 2005 16:37:45 +0000, Steve Taylor
wrote:

A funny thing, but 90% "remember" Serrurier trusses wrongly. The
Serrurier truss extends from the pivot to the secondary, and another
truss extends from the pivot to the primary, balancing deflections and
keeping the planes of the primary and secondary aligned.

Just sticking poles on the primary box, doesn't make it Serrurier trussed

No, it doesn't, and I didn't mean to suggest that all such designs
utilize Serrurier trusses. But Serrurier really developed the concept of
using a truss to support the secondary, and is rightfully remembered for
this- not unlike we call a certain class of mount Dobsonian even if it
doesn't utilize any of the materials popularized by John Dobson.

Serrurier developed his system for equatorial telescopes, which are much
more difficult to design than altaz telescopes. Simpler truss systems
are possible if gravity is only operating on one axis of the scope.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

RMOLLISE wrote:
I believe in credit where credit is due. If you think this person
deserves recognition as the "inventor" of truss tube scopes, spread the
word. Give presentations on him at star parties and clubs. Write
articles for astronomy mags, etc.

And make it about him rather than about tearing others like Dobson down
in the process.

Clear skies,
Greg

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
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